Welcome to LLVM! In order to get started, you first need to know some
basic information.

First, LLVM comes in three pieces. The first piece is the LLVM
suite. This contains all of the tools, libraries, and header files
needed to use the low level virtual machine. It contains an
assembler, disassembler, bitcode analyzer and bitcode optimizer. It
also contains basic regression tests that can be used to test the LLVM
tools and the GCC front end.

The second piece is the GCC front end. This component provides a version of
GCC that compiles C and C++ code into LLVM bitcode. Currently, the GCC front
end uses the GCC parser to convert code to LLVM. Once
compiled into LLVM bitcode, a program can be manipulated with the LLVM tools
from the LLVM suite.

There is a third, optional piece called Test Suite. It is a suite of programs
with a testing harness that can be used to further test LLVM's functionality
and performance.

Specify for directory the full pathname of where you
want the LLVM tools and libraries to be installed (default
/usr/local).

--with-llvmgccdir=directory

Optionally, specify for directory the full pathname of the
C/C++ front end installation to use with this LLVM configuration. If
not specified, the PATH will be searched. This is only needed if you
want to run test-suite or do some special kinds of LLVM builds.

--enable-spec2000=directory

Enable the SPEC2000 benchmarks for testing. The SPEC2000
benchmarks should be available in
directory.

Build the LLVM Suite:

gmake -k |& tee gnumake.out
# this is csh or tcsh syntax

If you get an "internal compiler error (ICE)" or test failures, see
below.

Note that you will need about 1-3 GB of space for a full LLVM build in Debug
mode, depending on the system (it is so large because of all the debugging
information and the fact that the libraries are statically linked into multiple
tools). If you do not need many of the tools and you are space-conscious, you
can pass ONLY_TOOLS="tools you need" to make. The Release build
requires considerably less space.

The LLVM suite may compile on other platforms, but it is not
guaranteed to do so. If compilation is successful, the LLVM utilities should be
able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code
generation should work as well, although the generated native code may not work
on your platform.

The GCC front end is not very portable at the moment. If you want to get it
to work on another platform, you can download a copy of the source and try to compile it on your platform.

Compiling LLVM requires that you have several software packages
installed. The table below lists those required packages. The Package column
is the usual name for the software package that LLVM depends on. The Version
column provides "known to work" versions of the package. The Notes column
describes how LLVM uses the package and provides other details.

LLVM is very demanding of the host C++ compiler, and as such tends to expose
bugs in the compiler. In particular, several versions of GCC crash when trying
to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
successfully with them (however, see important notes below). Other versions
of GCC will probably work as well. GCC versions listed
here are known to not work. If you are using one of these versions, please try
to upgrade your GCC to something more recent. If you run into a problem with a
version of GCC not listed here, please let
us know. Please use the "gcc -v" command to find out which version
of GCC you are using.

GCC versions prior to 3.0: GCC 2.96.x and before had several
problems in the STL that effectively prevent it from compiling LLVM.

GCC 3.2.2 and 3.2.3: These versions of GCC fails to compile LLVM with
a bogus template error. This was fixed in later GCCs.

GCC 3.3.2: This version of GCC suffered from a serious bug which causes it to crash in
the "convert_from_eh_region_ranges_1" GCC function.

Cygwin GCC 3.3.3: The version of GCC 3.3.3 commonly shipped with
Cygwin does not work. Please upgrade
to a newer version if possible.

SuSE GCC 3.3.3: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
possibly others) does not compile LLVM correctly (it appears that exception
handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
to a newer version of GCC.

GCC 3.4.0 on linux/x86 (32-bit): GCC miscompiles portions of the
code generator, causing an infinite loop in the llvm-gcc build when built
with optimizations enabled (i.e. a release build).

GCC 3.4.2 on linux/x86 (32-bit): GCC miscompiles portions of the
code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
correctly compiles LLVM at -O2. A work around is to build release LLVM
builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."

GCC 3.4.4 (CodeSourcery ARM 2005q3-2): this compiler miscompiles LLVM
when building with optimizations enabled. It appears to work with
"make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1" or build a debug
build.

IA-64 GCC 4.0.0: The IA-64 version of GCC 4.0.0 is known to
miscompile LLVM.

Apple Xcode 2.3: GCC crashes when compiling LLVM at -O3 (which is the
default with ENABLE_OPTIMIZED=1. To work around this, build with
"ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".

GCC 4.1.1: GCC fails to build LLVM with template concept check errors
compiling some files. At the time of this writing, GCC mainline (4.2)
did not share the problem.

GCC 4.1.1 on X86-64/amd64: GCC
miscompiles portions of LLVM when compiling llvm itself into 64-bit
code. LLVM will appear to mostly work but will be buggy, e.g. failing
portions of its testsuite.

GCC 4.3.3 (Debian 4.3.3-10) on ARM: Miscompiles parts of LLVM 2.6
when optimizations are turned on. The symptom is an infinite loop in
FoldingSetImpl::RemoveNode while running the code generator.

GCC 4.3.5 and GCC 4.4.5 on ARM: These can miscompile value >>
1 even at -O0. A test failure in test/Assembler/alignstack.ll is
one symptom of the problem.

GNU ld 2.16.X. Some 2.16.X versions of the ld linker will produce very
long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
defined in a discarded section. You can safely ignore these messages as they are
erroneous and the linkage is correct. These messages disappear using ld
2.17.

GNU binutils 2.17: Binutils 2.17 contains a bug which
causes huge link times (minutes instead of seconds) when building LLVM. We
recommend upgrading to a newer version (2.17.50.0.4 or later).

GNU Binutils 2.19.1 Gold: This version of Gold contained
a bug
which causes intermittent failures when building LLVM with position independent
code. The symptom is an error about cyclic dependencies. We recommend
upgrading to a newer version of Gold.

The remainder of this guide is meant to get you up and running with
LLVM and to give you some basic information about the LLVM environment.

The later sections of this guide describe the general layout of the the LLVM source tree, a simple example using the LLVM tool chain, and links to find more information about LLVM or to get
help via e-mail.

Throughout this manual, the following names are used to denote paths
specific to the local system and working environment. These are not
environment variables you need to set but just strings used in the rest
of this document below. In any of the examples below, simply replace
each of these names with the appropriate pathname on your local system.
All these paths are absolute:

SRC_ROOT

This is the top level directory of the LLVM source tree.

OBJ_ROOT

This is the top level directory of the LLVM object tree (i.e. the
tree where object files and compiled programs will be placed. It
can be the same as SRC_ROOT).

LLVMGCCDIR

This is where the LLVM GCC Front End is installed.

For the pre-built GCC front end binaries, the LLVMGCCDIR is
llvm-gcc/platform/llvm-gcc.

In order to compile and use LLVM, you may need to set some environment
variables.

LLVM_LIB_SEARCH_PATH=/path/to/your/bitcode/libs

[Optional] This environment variable helps LLVM linking tools find the
locations of your bitcode libraries. It is provided only as a
convenience since you can specify the paths using the -L options of the
tools and the C/C++ front-end will automatically use the bitcode files
installed in its
lib directory.

If you have the LLVM distribution, you will need to unpack it before you
can begin to compile it. LLVM is distributed as a set of two files: the LLVM
suite and the LLVM GCC front end compiled for your platform. There is an
additional test suite that is optional. Each file is a TAR archive that is
compressed with the gzip program.

The files are as follows, with x.y marking the version number:

llvm-x.y.tar.gz

Source release for the LLVM libraries and tools.

llvm-test-x.y.tar.gz

Source release for the LLVM test-suite.

llvm-gcc-4.2-x.y.source.tar.gz

Source release of the llvm-gcc-4.2 front end. See README.LLVM in the root
directory for build instructions.

This will create an 'llvm' directory in the current
directory and fully populate it with the LLVM source code, Makefiles,
test directories, and local copies of documentation files.

If you want to get a specific release (as opposed to the most recent
revision), you can checkout it from the 'tags' directory (instead of
'trunk'). The following releases are located in the following
subdirectories of the 'tags' directory:

Release 2.9: RELEASE_29

Release 2.8: RELEASE_28

Release 2.7: RELEASE_27

Release 2.6: RELEASE_26

Release 2.5: RELEASE_25

Release 2.4: RELEASE_24

Release 2.3: RELEASE_23

Release 2.2: RELEASE_22

Release 2.1: RELEASE_21

Release 2.0: RELEASE_20

Release 1.9: RELEASE_19

Release 1.8: RELEASE_18

Release 1.7: RELEASE_17

Release 1.6: RELEASE_16

Release 1.5: RELEASE_15

Release 1.4: RELEASE_14

Release 1.3: RELEASE_13

Release 1.2: RELEASE_12

Release 1.1: RELEASE_11

Release 1.0: RELEASE_1

If you would like to get the LLVM test suite (a separate package as of 1.4),
you get it from the Subversion repository:

GIT mirrors are available for a number of LLVM subprojects. These mirrors
sync automatically with each Subversion commit and contain all necessary
git-svn marks (so, you can recreate git-svn metadata locally). Note that right
now mirrors reflect only trunk for each project. You can do the
read-only GIT clone of LLVM via:

Before configuring and compiling the LLVM suite (or if you want to use just the LLVM
GCC front end) you can optionally extract the front end from the binary distribution.
It is used for running the LLVM test-suite and for compiling C/C++ programs. Note that
you can optionally build llvm-gcc yourself after building the
main LLVM repository.

To install the GCC front end, do the following (on Windows, use an archival tool
like 7-zip that understands gzipped tars):

cd where-you-want-the-front-end-to-live

gunzip --stdout llvm-gcc-4.2-version-platform.tar.gz | tar -xvf
-

Once the binary is uncompressed, if you're using a *nix-based system, add a symlink for
llvm-gcc and llvm-g++ to some directory in your path. If you're using a
Windows-based system, add the bin subdirectory of your front end installation directory
to your PATH environment variable. For example, if you uncompressed the binary to
c:\llvm-gcc, add c:\llvm-gcc\bin to your PATH.

If you now want to build LLVM from source, when you configure LLVM, it will
automatically detect llvm-gcc's presence (if it is in your path) enabling its
use in test-suite. Note that you can always build or install llvm-gcc at any
point after building the main LLVM repository: just reconfigure llvm and
test-suite will pick it up.

As a convenience for Windows users, the front end binaries for MinGW/x86 include
versions of the required w32api and mingw-runtime binaries. The last remaining step for
Windows users is to simply uncompress the binary binutils package from
MinGW into your front end installation directory. While the
front end installation steps are not quite the same as a typical manual MinGW installation,
they should be similar enough to those who have previously installed MinGW on Windows systems.

uncompress archived binutils directories (not the tar file) into the current directory

The binary versions of the LLVM GCC front end may not suit all of your needs. For
example, the binary distribution may include an old version of a system header
file, not "fix" a header file that needs to be fixed for GCC, or it may be linked with
libraries not available on your system. In cases like these, you may want to try
building the GCC front end from source. Thankfully,
this is much easier now than it was in the past.

We also do not currently support updating of the GCC front end by manually overlaying
newer versions of the w32api and mingw-runtime binary packages that may become available
from MinGW. At this time, it's best to think of the MinGW LLVM GCC front end binary as
a self-contained convenience package that requires Windows users to simply download and
uncompress the GNU Binutils binary package from the MinGW project.

Regardless of your platform, if you discover that installing the LLVM GCC front end
binaries is not as easy as previously described, or you would like to suggest improvements,
please let us know how you would like to see things improved by dropping us a note on our
mailing list.

Once checked out from the Subversion repository, the LLVM suite source
code must be
configured via the configure script. This script sets variables in the
various *.in files, most notably llvm/Makefile.config and
llvm/include/Config/config.h. It also populates OBJ_ROOT with
the Makefiles needed to begin building LLVM.

The following environment variables are used by the configure
script to configure the build system:

Variable

Purpose

CC

Tells configure which C compiler to use. By default,
configure will look for the first GCC C compiler in
PATH. Use this variable to override
configure's default behavior.

CXX

Tells configure which C++ compiler to use. By default,
configure will look for the first GCC C++ compiler in
PATH. Use this variable to override
configure's default behavior.

The following options can be used to set or enable LLVM specific options:

--with-llvmgccdir

Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
The value of this option should specify the full pathname of the C/C++ Front
End to be used. If this option is not provided, the PATH will be searched for
a program named llvm-gcc and the C/C++ FrontEnd install directory will
be inferred from the path found. If the option is not given, and no llvm-gcc
can be found in the path then a warning will be produced by
configure indicating this situation. LLVM may still be built with
the tools-only target but attempting to build the runtime libraries
will fail as these libraries require llvm-gcc and llvm-g++. See
Install the GCC Front End for details on installing
the C/C++ Front End. See
Bootstrapping the LLVM C/C++ Front-End
for details on building the C/C++ Front End.

--with-tclinclude

Path to the tcl include directory under which tclsh can be
found. Use this if you have multiple tcl installations on your machine and you
want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
dejagnu based test suite in llvm/test. If you don't specify this
option, the LLVM configure script will search for the tcl 8.4 and 8.3
releases.

--enable-optimized

Enables optimized compilation (debugging symbols are removed
and GCC optimization flags are enabled). Note that this is the default
setting if you are using the LLVM distribution. The default behavior
of an Subversion checkout is to use an unoptimized build (also known as a
debug build).

--enable-debug-runtime

Enables debug symbols in the runtime libraries. The default is to strip
debug symbols from the runtime libraries.

--enable-jit

Compile the Just In Time (JIT) compiler functionality. This is not
available
on all platforms. The default is dependent on platform, so it is best
to explicitly enable it if you want it.

--enable-targets=target-option

Controls which targets will be built and linked into llc. The default
value for target_options is "all" which builds and links all
available targets. The value "host-only" can be specified to build only a
native compiler (no cross-compiler targets available). The "native" target is
selected as the target of the build host. You can also specify a comma
separated list of target names that you want available in llc. The target
names use all lower case. The current set of targets is: alpha, ia64, powerpc, skeleton, sparc, x86.

--enable-doxygen

Look for the doxygen program and enable construction of doxygen based
documentation from the source code. This is disabled by default because
generating the documentation can take a long time and producess 100s of
megabytes of output.

--with-udis86

LLVM can use external disassembler library for various purposes (now it's
used only for examining code produced by JIT). This option will enable usage
of udis86 x86 (both 32 and 64
bits) disassembler library.

Once you have configured LLVM, you can build it. There are three types of
builds:

Debug Builds

These builds are the default when one is using an Subversion checkout and
types gmake (unless the --enable-optimized option was
used during configuration). The build system will compile the tools and
libraries with debugging information. To get a Debug Build using the
LLVM distribution the --disable-optimized option must be passed
to configure.

Release (Optimized) Builds

These builds are enabled with the --enable-optimized option to
configure or by specifying ENABLE_OPTIMIZED=1 on the
gmake command line. For these builds, the build system will
compile the tools and libraries with GCC optimizations enabled and strip
debugging information from the libraries and executables it generates.
Note that Release Builds are default when using an LLVM distribution.

Profile Builds

These builds are for use with profiling. They compile profiling
information into the code for use with programs like gprof.
Profile builds must be started by specifying ENABLE_PROFILING=1
on the gmake command line.

Once you have LLVM configured, you can build it by entering the
OBJ_ROOT directory and issuing the following command:

% gmake

If the build fails, please check here to see if you
are using a version of GCC that is known not to compile LLVM.

If you have multiple processors in your machine, you may wish to use some of
the parallel build options provided by GNU Make. For example, you could use the
command:

% gmake -j2

There are several special targets which are useful when working with the LLVM
source code:

gmake clean

Removes all files generated by the build. This includes object files,
generated C/C++ files, libraries, and executables.

gmake dist-clean

Removes everything that gmake clean does, but also removes files
generated by configure. It attempts to return the source tree to the
original state in which it was shipped.

gmake install

Installs LLVM header files, libraries, tools, and documentation in a
hierarchy
under $PREFIX, specified with ./configure --prefix=[dir], which
defaults to /usr/local.

gmake -C runtime install-bytecode

Assuming you built LLVM into $OBJDIR, when this command is run, it will
install bitcode libraries into the GCC front end's bitcode library
directory. If you need to update your bitcode libraries,
this is the target to use once you've built them.

Please see the Makefile Guide for further
details on these make targets and descriptions of other targets
available.

It is also possible to override default values from configure by
declaring variables on the command line. The following are some examples:

gmake ENABLE_OPTIMIZED=1

Perform a Release (Optimized) build.

gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1

Perform a Release (Optimized) build without assertions enabled.

gmake ENABLE_OPTIMIZED=0

Perform a Debug build.

gmake ENABLE_PROFILING=1

Perform a Profiling build.

gmake VERBOSE=1

Print what gmake is doing on standard output.

gmake TOOL_VERBOSE=1

Ask each tool invoked by the makefiles to print out what it is doing on
the standard output. This also implies VERBOSE=1.

Every directory in the LLVM object tree includes a Makefile to build
it and any subdirectories that it contains. Entering any directory inside the
LLVM object tree and typing gmake should rebuild anything in or below
that directory that is out of date.

It is possible to cross-compile LLVM itself. That is, you can create LLVM
executables and libraries to be hosted on a platform different from the
platform where they are build (a Canadian Cross build). To configure a
cross-compile, supply the configure script with --build and
--host options that are different. The values of these options must
be legal target triples that your GCC compiler supports.

The result of such a build is executables that are not runnable on
on the build host (--build option) but can be executed on the compile host
(--host option).

The LLVM build system is capable of sharing a single LLVM source tree among
several LLVM builds. Hence, it is possible to build LLVM for several different
platforms or configurations using the same source tree.

This is accomplished in the typical autoconf manner:

Change directory to where the LLVM object files should live:

% cd OBJ_ROOT

Run the configure script found in the LLVM source
directory:

% SRC_ROOT/configure

The LLVM build will place files underneath OBJ_ROOT in directories
named after the build type:

If you're running on a Linux system that supports the "binfmt_misc"
module, and you have root access on the system, you can set your system up to
execute LLVM bitcode files directly. To do this, use commands like this (the
first command may not be required if you are already using the module):

This directory contains public header files exported from the LLVM
library. The three main subdirectories of this directory are:

llvm/include/llvm

This directory contains all of the LLVM specific header files. This
directory also has subdirectories for different portions of LLVM:
Analysis, CodeGen, Target, Transforms,
etc...

llvm/include/llvm/Support

This directory contains generic support libraries that are provided with
LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
and a Command Line option processing library store their header files here.

llvm/include/llvm/Config

This directory contains header files configured by the configure
script. They wrap "standard" UNIX and C header files. Source code can
include these header files which automatically take care of the conditional
#includes that the configure script generates.

This directory contains files that describe various target architectures
for code generation. For example, the llvm/lib/Target/X86
directory holds the X86 machine description while
llvm/lib/Target/CBackend implements the LLVM-to-C converter.

llvm/lib/CodeGen/

This directory contains the major parts of the code generator: Instruction
Selector, Instruction Scheduling, and Register Allocation.

llvm/lib/Debugger/

This directory contains the source level debugger library that makes
it possible to instrument LLVM programs so that a debugger could identify
source code locations at which the program is executing.

llvm/lib/ExecutionEngine/

This directory contains libraries for executing LLVM bitcode directly
at runtime in both interpreted and JIT compiled fashions.

llvm/lib/Support/

This directory contains the source code that corresponds to the header
files located in llvm/include/Support/.

llvm/lib/System/

This directory contains the operating system abstraction layer that
shields LLVM from platform-specific coding.

This directory contains projects that are not strictly part of LLVM but are
shipped with LLVM. This is also the directory where you should create your own
LLVM-based projects. See llvm/projects/sample for an example of how
to set up your own project.

This directory contains libraries which are compiled into LLVM bitcode and
used when linking programs with the GCC front end. Most of these libraries are
skeleton versions of real libraries; for example, libc is a stripped down
version of glibc.

Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
end to compile.

This is not a directory in the normal llvm module; it is a separate
Subversion
module that must be checked out (usually to projects/test-suite).
This
module contains a comprehensive correctness, performance, and benchmarking
test
suite for LLVM. It is a separate Subversion module because not every LLVM
user is
interested in downloading or building such a comprehensive test suite. For
further details on this test suite, please see the
Testing Guide document.

The tools directory contains the executables built out of the
libraries above, which form the main part of the user interface. You can
always get help for a tool by typing tool_name -help. The
following is a brief introduction to the most important tools. More detailed
information is in the Command Guide.

bugpoint

bugpoint is used to debug
optimization passes or code generation backends by narrowing down the
given test case to the minimum number of passes and/or instructions that
still cause a problem, whether it is a crash or miscompilation. See HowToSubmitABug.html for more information
on using bugpoint.

llvmc

The LLVM Compiler Driver. This program can
be configured to utilize both LLVM and non-LLVM compilation tools to enable
pre-processing, translation, optimization, assembly, and linking of programs
all from one command line. llvmc also takes care of processing the
dependent libraries found in bitcode. This reduces the need to get the
traditional -l<name> options right on the command line. Please
note that this tool, while functional, is still experimental and not feature
complete.

llvm-ar

The archiver produces an archive containing
the given LLVM bitcode files, optionally with an index for faster
lookup.

llvm-ld is a general purpose and extensible linker for LLVM.
This is the linker invoked by llvmc. It performs standard link time
optimizations and allows optimization modules to be loaded and run so that
language specific optimizations can be applied at link time.

llvm-link

llvm-link, not surprisingly, links multiple LLVM modules into
a single program.

lli

lli is the LLVM interpreter, which
can directly execute LLVM bitcode (although very slowly...). For architectures
that support it (currently x86, Sparc, and PowerPC), by default, lli
will function as a Just-In-Time compiler (if the functionality was compiled
in), and will execute the code much faster than the interpreter.

llc

llc is the LLVM backend compiler, which
translates LLVM bitcode to a native code assembly file or to C code (with
the -march=c option).

llvm-gcc

llvm-gcc is a GCC-based C frontend that has been retargeted to
use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
bitcode or assembly (with the -emit-llvm option) instead of the
usual machine code output. It works just like any other GCC compiler,
taking the typical -c, -S, -E, -o options that are typically used.
Additionally, the the source code for llvm-gcc is available as a
separate Subversion module.

opt

opt reads LLVM bitcode, applies a series of LLVM to LLVM
transformations (which are specified on the command line), and then outputs
the resultant bitcode. The 'opt -help' command is a good way to
get a list of the program transformations available in LLVM.

opt can also be used to run a specific analysis on an input
LLVM bitcode file and print out the results. It is primarily useful for
debugging analyses, or familiarizing yourself with what an analysis does.

This directory contains utilities for working with LLVM source code, and some
of the utilities are actually required as part of the build process because they
are code generators for parts of LLVM infrastructure.

codegen-diff

codegen-diff is a script
that finds differences between code that LLC generates and code that LLI
generates. This is a useful tool if you are debugging one of them,
assuming that the other generates correct output. For the full user
manual, run `perldoc codegen-diff'.

emacs/

The emacs directory contains
syntax-highlighting files which will work with Emacs and XEmacs editors,
providing syntax highlighting support for LLVM assembly files and TableGen
description files. For information on how to use the syntax files, consult
the README file in that directory.

getsrcs.sh

The getsrcs.sh script finds
and outputs all non-generated source files, which is useful if one wishes
to do a lot of development across directories and does not want to
individually find each file. One way to use it is to run, for example:
xemacs `utils/getsources.sh` from the top of your LLVM source
tree.

llvmgrep

This little tool performs an "egrep -H -n" on each source file in LLVM and
passes to it a regular expression provided on llvmgrep's command
line. This is a very efficient way of searching the source base for a
particular regular expression.

makellvm

The makellvm script compiles all
files in the current directory and then compiles and links the tool that
is the first argument. For example, assuming you are in the directory
llvm/lib/Target/Sparc, if makellvm is in your path,
simply running makellvm llc will make a build of the current
directory, switch to directory llvm/tools/llc and build it,
causing a re-linking of LLC.

NewNightlyTest.pl and
NightlyTestTemplate.html

These files are used in a
cron script to generate nightly status reports of the functionality of
tools, and the results can be seen by following the appropriate link on
the LLVM homepage.

TableGen/

The TableGen directory contains
the tool used to generate register descriptions, instruction set
descriptions, and even assemblers from common TableGen description
files.

vim/

The vim directory contains
syntax-highlighting files which will work with the VIM editor, providing
syntax highlighting support for LLVM assembly files and TableGen
description files. For information on how to use the syntax files, consult
the README file in that directory.

This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
so we only include instructions for llvm-gcc4.

Note: The gcc4 frontend's invocation is considerably different
from the previous gcc3 frontend. In particular, the gcc4 frontend does not
create bitcode by default: gcc4 produces native code. As the example below illustrates,
the '--emit-llvm' flag is needed to produce LLVM bitcode output. For makefiles and
configure scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
output.

This document is just an introduction on how to use LLVM to do
some simple things... there are many more interesting and complicated things
that you can do that aren't documented here (but we'll gladly accept a patch
if you want to write something up!). For more information about LLVM, check
out: